1. Field of the Invention
The present invention relates to a locking cover assembly for dead bolt locks with actuator shafts, and more particularly, to the type that is used in conjunction with a closure member.
2. Description of the Related Art
A conventional dead bolt lock assembly includes an actuator shaft with an end extending towards the protected interior. A cylindrical or cover assembly is typically mounted at the end of the actuator shaft to permit a user to rotate it and thus cause the dead bolt to protrude or come within the closure member (usually a door). The conventional dead bolt assembly has an actuator shaft that has a rectangular cross-section, in most cases. The present invention permits a user to selectively limit the rotation of the actuator shaft by cooperatively positioning stopper members in the cover in one of three predetermined positions. In this manner, an occupant of the protected premises may selectively position the cover to (a) neutral and the dead bolt assembly operates normally; (b) limit the rotation of the actuator shaft to prevent the dead bolt from protruding out; and (c) limit the rotation of the actuator shaft to prevent the dead bolt from retracting inside the closure member (locking the door). Under (b) and (c) a user outside the protected premises would not be able to lock the door (if in position b) or unlock (if in position c) the closure member.
The applicant believes that the closest reference corresponds to U.S. Pat. No. 5,313,812 issued to Eklund for a door lock security system. However, it differs from the present invention because it is a voluminous and complicated device that needs to be mechanically coupled with handle 46 which comes in a variety of designs, including round design (for which it will not operate). Also, off-centered portion 14 requires a structural modification of the closure member with the consequent inconvenience Finally, and more important, the patented device has a bulky "immobilizer" handle 46 whereas the present invention, as discussed above, permits a user to readily select one of three positions in a minimum of space.
Another relevant reference is U.S. Pat. No. 5,515,704 issued to Van Nguyen on May 14, 1996 for a security lock for a dead bolt lock assembly. As in the previous patent, the objective is to immobilize handle 36 requiring a mechanical structure to be attached to the closure member.
The present invention is an improvement over pending and allowed patent applicant Ser. No. 08/731,327 filed on Oct. 15, 1996 and assigned to a common assignee. It differs in that it does not require an annular threaded flange member and the spring is smaller in diameter thusmanufacturing and assembly is substantially simpler with less components.
Other patents describing the closest subject matter provide for a number of more or less complicated features that fail to solve the problem in an efficient and economical way. None of these patents suggest the novel features of the present invention.